The $1 Pocket Microscope

It took about six months for the jungle to kill Aaron Pomerantz’s microscope.

Pomerantz, an entomologist working with Rainforest Expeditions, had been doing fieldwork in the remote Tambopata Research Centre, nestled within the Peruvian Amazon. At first, he had examined his minute specimens with the center’s fancy optical microscope. But thanks to the sweltering humidity, water started condensing on all the microscope’s glass components. Soon, it was caked in fungus. “Everything out here gets consumed by the jungle,” says Pomerantz.

An entomologist without a microscope is like an astronomer without a telescope, so Pomerantz needed a replacement. Ideally, he wanted something portable enough to carry while hiking, robust enough to withstand the Amazon, and cheap enough to avoid breaking his budget. After a quick search, he learned that 5,000 miles away, a Stanford University engineer named Manu Prakash had been building exactly what he wanted.

Four years ago, during a visit to Thailand, Prakash was amazed to see that several remote clinics had state-of-the-art microscopes—but never used them. “They’re so expensive that everyone’s scared of touching them,” he explains. Better to just lock them up. That, he thought, was absurd. So he set out to make something better. “Something like a pencil,” he says. “The pencil can be with you at all times, it works all the time, and it’s robust.”

After years of tinkering, he came up with the Foldscope. It’s a microscope that comes as a single sheet of thick paper: you snap out the components, fold them origami-style, and thread them together. Ten minutes later, you have a device that weighs 9 grams, fits in a pocket, holds regular microscope slides, and can magnify their contents more than 2,000 times using a small built-in lens. That’s good enough to visualize everything from a ladybug’s claws to a colony of bacteria. Best of all, the device costs less than a dollar to manufacture.

At first, Prakash set up a makeshift factory in his lab and printed around 50,000 of the Foldscopes. He and his team members have since shipped 10,000 of those out by hand, as part of a broad beta-test.

Pomerantz was one of the lucky recipients. “It has been so useful for my fieldwork,” he says, having used it to study plant cells, mites, fly larvae, and single-celled parasites. “It feels like holding a piece of paper, because that’s what it sort of is. It’s also really robust. I take really long hikes in the jungle, so it gets dumped on by rain and mud—and it still works.”

There are other such cheap microscopes, including some that can be fitted onto cellphones. But Prakash thinks such designs are still subservient to the expensive technology that they deign to replace. “We wanted to make a device that functions on its own,” he says. “The idea of designing for a cellphone rubs me the wrong way.”

The Foldscope can, however, be used with a phone. As Pomerantz demonstrates in a video, if you stick a smartphone over the eyepiece, you can take pictures or record videos of whatever’s in the frame. If you stick a light source behind the Foldscope, you can turn it into a projector. And with small tweaks, the vanilla Foldscope can be transformed into a dark-field microscope (which visualizes objects against a black background) or a fluorescence microscope (which studies objects that glow under certain lights). “It’s a very hackable object,” says Prakash. “Culturally, paper is an object that kids are very happy to play with.”

The scope’s uses are manifold. Field biologists like Pomerantz can study organisms in their natural settings, rather than having to first ship them back to a laboratory. Health workers in poor countries can detect the parasites that cause malaria, leishmaniasis, schistosomiasis, and other tropical diseases.

But Prakash is most excited about amateurs just using the Foldscope to look at the world around them. “The biggest thing we’re trying to do is to make people curious,” he says. “Our ambition is that every kid should be able to carry a microscope in their pocket.” To make that happen, Prakash is now courting larger organizations that can take over the manufacturing and distribution. And he is convinced that once the scopes get in the hands of users, the rest will be easy. For example, when one of Pomerantz’s colleagues gave an unassembled Foldscope to Mexican schoolchildren who didn’t speak English; the kids just ignored the instructions and put together the microscope on their own. Then, they started looking at anything they could get their hands on.

“The Foldscope doesn’t tell you what to do. It’s open-ended,” says Prakash. “In biology classrooms, you read about something and then you look. But when you become a scientist, you look first. Then, you become so curious that you pile through everything that’s known so you can venture into the unknown.” That’s the spirit he wants to inculcate in the Foldscope’s users.

None of this is groundbreaking. Then again, one of the most important discoveries in biology emerged from such casual and inauspicious acts. Around 350 years ago, in the Dutch trading city of Delft, an untrained draper named Antony van Leeuwenhoek started peering at infinitesimally small objects through microscopes of his own making. With unparalleled skill, he would grind smooth spherical lenses, just a couple of millimeters across. He then sandwiched these between brass plates to create a small microscope, half the size of a credit card. By holding it up to his eye and squinting through the mounted lens, he started studying the worlds of animal hairs, fly heads, plant tissues, and red blood cells.

In 1674, he turned his microscope onto samples of water collected from a nearby lake. He saw thousands of tiny creatures, whose motion “was so swift, and so various upwards, downwards and round about that ‘twas wonderful to see.” Those were protists, and Leeuwenhoek had become the first person in history to see them. The following year, he looked at rainwater that had collected in a blue pot outside his house. Again, a microscopic menagerie revealed itself, some of which were even smaller than those from the lake. They were bacteria and, again, they were making their first appearance to human eyes. As one historian wrote, “Almost everything [Leeuwenhoek] saw, he was the first human ever to see.”

Everything we know about microbes, from the beneficial ones that share our bodies to the infectious ones that riddle us with disease, bloomed from those early observations. And Leeuwenhoek shared many characteristics with your average Foldscope user. He was an amateur, untrained in science. He used a simple, flattened device with a single lens that he held close to his face. And most of all, he was relentlessly curious.

Why, you might ask, did he even think to look at a drop of stagnant rainwater in the first place? It is perhaps the same urge that drives an engineer to check out the tulips by his bed, or that compels a six-year-old child to study snow and ice. Microscopes have a long history of enabling curiosity, and so catalyzing discovery. The Foldscope is just the latest part of that tradition.

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